Polyisocyanates and mixtures thereof



are he Patented July 13, 1954 PATENT OFFICE POLYISOCYANATES AND MIXTURESTHEREOF Nelson V. Seeger and Ernest E. Fauser, Cuyahoga Falls, Ohio,assignors, to The Goodyear Tire corporation of Ohio by mesneassignments, & Rubber Company, a

No Drawing. Application January 17, 1951,

Serial N o.

10 Claims.

This invention relates to new compositions of matter and to methods fortheir preparation. More particularly, it relates to organicpolyisocyanates and still more particularly to mixtures of organicpolyisocyanates and to methods for 5 their preparation.

The broad object of this invention is to pro vide for the preparation ofpolyisocyanates and mixtures thereof which contain a controlled maximumamount of the diisocyanate. A particular object of this invention is thepreparation of polyisocyanates from relatively inexpensive rawmaterials. Other objects will appear as the description proceeds.

According to the practice of this invention, an aryl mono primary aminein controlled molecular amounts is reacted with an aliphatic or aromaticaldehyde or ketone in controlled molecular amounts to yield a mixtureofsecondary polyamines. These secondary amines are subjected torearrangement to primary polyarnines by means of a mineral acids Theprimary poly-amines are then phosgenated to the polyisocyanates.

Using aniline as a representative aryl mono primary amine andformaldehyde as a representative aldehyde, typical reactions arebelieved to take place as follows:

COE4NH2 C sHs-NH2 Hz 0 diaminc H H mineral acid I z CoHa C aH4-NH2 CeH4-NH2 HCH HOH C oHaNH2 CBH5NH2 CHzO JoHa-N-Hz H20 HO n 110 H ZsH4NH2kHz-NH; triamine H H l IH mineral acid/ I l/ CaH5 2. CeHr-NH:

H CH

eH3NH2 CuH5NH2 CHzO penta-amlne etc. H H

0H3NH2 tHi-NHZ tetra-amine The polyamines formed as indicated areconverted to the polyisocyanates by reaction with phosgene. It should beunderstood that the formation of the polyamines is not a step-wisereaction but rather a reaction in which the formation of the diamine,triamine, tetra-amine, and higher amines is proceeding simultaneouslywith the result that the completed reaction product is a mixture of the'polyamines. The mineral acid is present in the reacting mixture toaccomplish the rearrangement of'the secondary amino groups as they formin the constructionof the polyamine molecule. rearrangement occurs afterthe secondary amino group forms and before the next higher polymeris'formed by reaction with another molecule of amine and aldehyde orketone.

This invention is concerned with "the formation of mixtures ofpolyisocyanates in which the diisocyanate portion is present inanamo-unt not to exceed approximately 40% by weight of the mixture. Thisis accomplished by controlling the molecular ratio of amine to aldehydeor ketone in a range of from 4:2.5 to 4:35 with the amine being presentin the larger molecular amount. A ratio of 422.5 yields a mixture ofpolyamines containing approximately 40% diamine by weight, whileincreasing the aldehyde or ketone to aoratio of 4:3.5t'yields amixturecontaining approximately 15%diamine by weight,

1 with the balance in each case being the triamine,

and higher amines. The polyamine mixtures are reacted with phosgene, asindicated, to obtain a mixture of polyisocyanates.

The mixture of polyisocyanates resulting from reacting the polyamineswith phosgene may be used to advantage in polymeric reactions withcompounds containing reactive hydrogens. The diisocyanate portion of themixture can be substantially removed therefrom by distillation.Separation of the higher polyisocyanates is more difiicult since thesematerials are resinous in It is believed that the.

character. The separation of the mixture of polyisocyanates into itscomponents is not necessary for some uses as, for instance, in thecrosslinking of the diisocyanate-modified polyesters and polyesteramidesdescribed in co-pending applications Serial Nos. 170,055 and 170,056,filed June 23, 1950, both now abandoned. When employed in suchreactions, the mixtures of polyisocyanates containing up to 40% byweight of the diisocyanate may prove advantageous, or the diisocyanatemay be substantially removed by distillation of the product leaving amixture containing polyisocyanates with more than two --NCO equivalentsper mol. The latter purified mixture may also be used as cross-linkingagents for diisocyanate-modified polyesters and polyesteramides wherethe important consideraction is not the purity of the reactant used, butrather the number of -NCO equivalents present in a given amount of thereactant.

The number of -NH2 or -NCO groups in a given amount of the mixtures ofreaction products can be determined by titration procedures well knownin the art. The determinations show the neutral equivalent of thepolyamines and the amine equivalent of the polyisocyanates. The amineequivalent is defined as the number of grams of isocyanate which isconsumed by one gram mol of a secondary amine, such as di-nbutyl amine,in the formation of the corresponding urea. The procedure involved inmaking this determination is described in an article by Siggia andHanna, Ind. and Eng. Chem. Analytical Ed. 20, 1084 (1948). Since theamine equivalent of any pure diisocyanate is known, it is possible todetermine the presence of the higher polyisocyanates by analyzing themixture to show an amine equivalent higher than the theoreticalequivalent of the diisocyanate.

In the formation of the polyamine molecule it is believed that thecarbon atom of the aldehyde or ketone which attaches to the arylenenucleus is located in a position para to the nitrogen unless thatposition is blocked by the presence of another substituent in which casethe linkage is probably in a position ortho to the nitrogen. It ispossible that in the formation of the polyamine more than twosubstitutions in the arylene nucleus will result. For instance, againtaking aniline and formaldehyde as representative reactants, it ispossible that a polyisocyanate molecule of the following formula couldbe present in the reaction product, substitution occurring in the paraand ortho positions:

NCO

NCO A structural formula which defines the mixture of polyisocyanates inthe reaction product is X Y X l A l ooNI t I|t-NO X Y X in which R and Rare arylene radicals, Y is selected from the group consisting ofhydrogen, alkyl, and aryl radicals, and X is selected from the groupconsisting of hydrogen and a radical defined by the formula in which R,X, and Y as defined above.

Alternatively the mixture of polyisocyanates may be described ascorresponding to the formula OCN-R(CY2R'NCO) n in which R and R arearylene radicals, Y is selected from the group consisting of hydrogen,alkyl, and aryl radicals, n is a whole number, and the (CY2-R-NCO)groups in excess of one are attached to an R radical.

Representative examples of the aryl mono pri mary amines which may beemployed in the formation of the polyarnines are aniline, the nuclearsubstituted phenyl amines such as ortho, meta, and para chloroaniline;ortho, meta, and para toluidine; ortho, meta, and para phe netidine;ortho, meta, and para anisidine; and ortho, meta, and para xylidine;ortho, meta, para xenyl amines, and alpha and beta naphthylamine.Mixtures of these aryl mono primary amines may also be used. Nuclearsubstituted aryl amines may be used so long as the substituted radicaldoes not contain hydrogen reactive with an isocyanate group. Thepresence of such reactive hydrogen in the phosgenated polyamine wouldpermit additional polymerization of the reaction product which is notdesired.

Representative examples of the aldehydes and ketones which may beemployed are the aliphatic aldehydes such as formaldehyde, acetaldehyde,propionaldehyde, butyraldehyde and nonylaldehyde, the aromatic aldehydessuch as benzaldehyde, the aliphatic ketones such as methyl ethyl ketone,acetone, the pentanones, and hexanones, and the aromatic ketones such asacetophenone, benzophenone and propiophenone. Mixtures of thesecompounds may also be used.

Preferred polyisocyanates are those resulting from the phosgenation ofthe polyamines resulting from the reaction of aniline with formaldehyde,benzaldehyde, acetaldehyde, methyl ethyl ketone or acetone; orthotoluidine with formaldehyde, benzaldehyde, acetaldehyde, methyl ethylketone or acetone; ortho chloraniline with formaldehyde, benzaldehyde,acetaldehyde, methyl ethyl ketone or acetone; ortho anisidine withformaldehyde, benzaldehyde, acetaldehyde, methyl ethyl ketone, oracetone; and alpha naphthyl amine with formaldehyde, benzaldehyde,acetaldehyde, methyl ethyl ketone, or acetone.

The practice of the invention is illustrated by the following examples.

1. Preparation of polyamine To 485 grams of aniline (5.2 moles) wasslowly added a mixture containing 229 milliliters of concentratedhydrochloric acid and 322 grams of 37% formalin (4.03 molesformaldehyde). The temperature of the reaction mixture was kept below 83C. by cooling. When all the reactants had been added, the solution wasgradually heated to C. and kept at this temperature for 5 hours. Toneutralize the acid, 117

showed that 27.7% by weight distilled over the range 240-245 C. undermm. pressure. This fraction, substantially pure diamine, showed aneutral equivalent of 100.1. The neutral equivalent of the pure diamineis 99. The residue (72.3% by weight) showed a neutral equivalent of109.3. From these analyses it is apparent that here is a mixture ofpolyamines in which the polyamines higher than the difunctional aminepredominate.

II. Synthesis of the polyisocyanate from the polyamine Three hundredforty-five grams (3.5 moles) of phosgene were dissolved in 700milliliters of chlorobenzene and chilled to below 0 C. To this solutionwas slowly added, with stirring, a hot solution of 2000 milliliters ofchlorobenzene containing 268 grams of the aniline-formaldehyde polyamineresin prepared according to I. The temperature of the reaction mixturewas held below C. The resin-phosgene complex separated as a yellowsolid, making a thick slurry. The reaction mixture was then slowlyheated to reflux over a period of 6 hours. During this time a slowstream of phosgene was bubbled through the mixture. Refiuxing continuedfor 30 minutes after which the phosgene was turned off. Heatingcontinued for 30 minutes more to remove the phosgene. The solution wascooled to room temperature and filtered. The filtrate was heated todrive ofi the solvent leaving a residue of resinous polyisocyanate. Theamine equivalent of the product was 136.1. The amine equivalent of thepure diisocyanate is 125.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

We claim:

1. A composition of matter comprising a mixture of polyisocyanatescorresponding to the formula in which R and R are arylene radicals, Y isselected from the group consisting of hydrogen, alkyl, and arylradicals, n is a whole number, and the (CY2-RNCO) groups in excess ofone are attached to an R radical, said mixture comprising from 0% to byweight of the diisocyanate and from 100% to 60% by weight of at leastone polyisocyanate containing more than two NCO equivalents per mol ofpolyisocyanate.

2. A composition of matter comprising a mixture of polyisocyanatescorresponding to the formula in which R and R. are phenylene radicals, Yis an alkyl radical, n is a whole number, and the (CI1YRNCO) groups inexcess of one are attached to an R radical, said mixture comprising from0% to 40% by weight of the diisocyanate and from to 60% by weight ofpolyisocyanates containing more than two NCO equivalents per mol ofpolyisocyanate.

3. A composition of matter comprising a mixture of polyisocyanatescorresponding the formula in which R and R, are phenylene radicals, n isa whole number, and the (CH2R'--NCO) groups in excess of one areattached to an R radical, said mixture comprising from 0 to 40% byweight of the diiosocyanate and from 100% to 60% by weight ofpclyisocyanates containing more than two NC'O equivalents per mol ofpolyisocyanate.

4. The compositions defined by claim 1 in which R and R are 5. Thecompositions defined by claim 1 in which R and R are 6. The compositionsdefined by claim 1 in which R and R are 7. The compositions defined byclaim 3 in which R. and R are com 8. The compositions defined by claim 4in which Y is hydrogen.

9. The compositions defined by claim 5 in which Y is hydrogen.

10. The compositions defined in claim 6 in which Y is hydrogen.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,029,954 Sutter Feb. 4, 1936 2,437,867 Verbanc Mar. 16, 1948FOREIGN PATENTS Number Country Date 404,469 Great Britain Jan. 18, 1934OTHER REFERENCES Bayer, Angewandte Chemie, A/59, September 194:7, p.264.

1. A COMPOSITION OF MATTER COMPRISING A MIXTURE OF POLYISOCYANATESCORRESPONDING TO THE FORMALA